Hilo

Today: Mostly sunny with isolated showers. Highs around 82 near the shore to 65 to 70 at 4000 feet. South winds up to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 65 near the shore to around 51 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 65 to 70 at 4000 feet. North winds up to 15 mph shifting to the east in the afternoon. Gusts up to 35 mph. Chance of rain 40 percent.

Kona

Today: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 71 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Tonight: Partly cloudy with isolated showers. Lows 65 to 71 near the shore to around 52 near 5000 feet. Light winds. Chance of rain 20 percent.

Saturday: Mostly sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs 80 to 85 near the shore to around 71 near 5000 feet. West winds up to 10 mph. Chance of rain 20 percent.

Waimea

Today: Breezy. Mostly sunny with isolated showers. Highs around 81 near the shore to 71 to 78 near 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 64 near the shore to 50 to 58 near 3000 feet. East winds 10 to 25 mph decreasing to up to 25 mph after midnight. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs around 81 near the shore to 71 to 78 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

Kohala

Today: Breezy. Mostly sunny with isolated showers. Highs around 81 near the shore to 71 to 78 near 3000 feet. East winds up to 20 mph increasing to 10 to 20 mph in the afternoon. Chance of rain 20 percent.

Tonight: Breezy. Partly cloudy with isolated showers. Lows around 64 near the shore to 50 to 58 near 3000 feet. East winds 10 to 25 mph decreasing to up to 25 mph after midnight. Chance of rain 20 percent.

Saturday: Breezy. Mostly sunny with isolated showers. Highs around 81 near the shore to 71 to 78 near 3000 feet. East winds up to 20 mph. Chance of rain 20 percent.

South Big Island

Today: Mostly sunny. Breezy. Highs around 83 near the shore to around 72 near 5000 feet. East winds up to 20 mph.

Tonight: Mostly clear. Breezy. Lows around 67 near the shore to around 51 near 5000 feet. East winds up to 20 mph shifting to the northeast 10 to 20 mph after midnight.

Saturday: Mostly sunny. Breezy. Isolated showers in the afternoon. Highs around 83 near the shore to around 72 near 5000 feet. East winds 10 to 25 mph decreasing to up to 25 mph in the afternoon. Chance of rain 20 percent.

Puna

Today: Mostly sunny with isolated showers. Highs around 82 near the shore to 65 to 70 at 4000 feet. South winds up to 15 mph shifting to the east in the afternoon. Chance of rain 20 percent.

Tonight: Mostly cloudy with scattered showers. Lows around 65 near the shore to around 51 at 4000 feet. North winds up to 15 mph. Chance of rain 50 percent.

Saturday: Mostly sunny. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 82 near the shore to 65 to 70 at 4000 feet. North winds up to 15 mph shifting to the east in the afternoon. Gusts up to 35 mph. Chance of rain 40 percent.

Waikoloa

Today: Mostly sunny. Highs around 82 near the shore to 66 to 73 above 4000 feet. Northeast winds up to 10 mph shifting to the north in the afternoon.

Tonight: Mostly clear. Breezy. Lows around 69 near the shore to 47 to 55 above 4000 feet. Southeast winds up to 20 mph.

Saturday: Mostly sunny. Highs around 82 near the shore to 66 to 73 above 4000 feet. East winds up to 15 mph shifting to the northwest in the afternoon.

Detailed Forecast

Synopsis

Moderate to locally breezy trade winds will prevail through Saturday, before lowering into the light to moderate range on Sunday. A few showers will affect windward areas, mainly during nights and mornings, while mainly dry conditions are expected in leeward areas. Light to moderate trades will hold in place Monday and Tuesday, but an increase in moisture should bring an uptick in trade wind showers, as well as a few more showers to leeward areas each afternoon. A potent upper level disturbance may bring an increase in rain chances to all or portions of the island chain during the middle to latter part of next week.

Discussion

Currently at the surface, an east to west oriented ridge of high pressure is positioned around 300 miles north of Kauai, and is driving moderate to locally breezy trade winds in the non- sheltered areas across the island chain early this morning. Infrared satellite imagery shows mostly clear to partly cloudy conditions, with a bit more cloud cover in some windward locales. Radar imagery shows a few very light showers moving into windward slopes and coasts, with dry conditions in leeward areas. Main short term focus revolves around trade wind trends and rain chances.
The surface ridge north of the state will move very little through Saturday, keeping moderate to locally breezy trade winds in place. A front approaching from the northwest will weaken the ridge north of the islands by Sunday, with a general light to moderate trade wind flow holding in place from the tail end of the weekend through the middle of next week.
As for the remaining weather details, very dry and stable conditions will hold in place through Sunday, with inversion heights holding around 5-6 kft and precipitable water values around 1 inch or less. A few showers will be possible over windward areas during this time, with mostly dry conditions expected in leeward locales. Weaker trades may allow for localized sea breezes and a few afternoon showers in leeward areas on Sunday however.
Inversion heights will rise and precipitable water values will climb to more typical levels Monday through Tuesday, which should bring an increase in trade wind showers. Showers will continue to favor windward and mauka areas, particularly during nights and mornings, with a few afternoon showers also developing in leeward areas. Both the GFS and the ECMWF show a pretty strong upper level trough moving through the region Wednesday and Thursday, which could bring an increase in rain chances to all or portions of the island chain.

Aviation

Breezy easterly trades across the state through tonight, will be reinforced by a ridge of high pressure north of the islands. Dry and relatively stable conditions associated with this pattern will continue to limit the areal coverage and intensity of showers through tonight, with any showers that do develop confined again to mainly windward areas through the TAF period. VFR conditions are expected to continue at most TAF sites, however a few windward showers may briefly generate MVFR cigs.
AIRMET Tango remains in effect for tempo moderate low level turbulence downwind of terrain for all islands. With the locally breezy trade winds expected to persist through Saturday, this AIRMET is likely to continue throughout the forecast period.

Marine

The high pressure ridge will remain in place north of the Hawaiian Islands through Saturday producing moderate to locally strong trade winds. An approaching cold front moving into the Central Pacific from the west will weaken this ridge and decrease wind speeds into the light to moderate range from Sunday into the middle of next week. A hybrid trade wind and near-shore sea breeze pattern will take hold over the region from Sunday onward.
The large west-northwest swell continues to trend higher at the Hanalei, Kauai buoy this morning, and the Waimea Bay buoy swell heights are following this upward trend with both sites reporting wave periods around 20 seconds. Buoy 1 (51001) northwest of Kauai at 1:40 AM HST reported 16 foot swell heights with a near 20 second period. These buoy reports are in line with the current forecast reasoning roughly 2 to 3 feet above GFS Wave model guidance.
Surf along exposed north and west facing shores will exceed High Surf Warning (HSW) levels today, then hold through much of Saturday, before beginning a gradual decline into early next week. Surf heights into a solid HSW range will peak today and Saturday, then decline into the High Surf Advisory range on Sunday, and then drop below advisory levels by Monday morning.
This large west-northwest swell will also bring Small Craft Advisory (SCA) seas to exposed waters. The SCA includes the windier waters near Maui County and the Big Island, and all waters exposed to this swell direction. SCA seas will likely linger through the weekend with weakening wind speeds on Sunday and Monday.
There is the chance for overwash from this large swell to impact the typical vulnerable low-lying coastal roadways. The best chance of overwash will occur around peak high tide times around midnight tonight.

HFO Watches/Warnings/Advisories

High Surf Warning until 6 PM HST Saturday for Niihau, Kauai Leeward, Waianae Coast, Oahu North Shore, Maui Windward West, Kona, Kohala, Kauai North, Molokai Windward, Molokai North, Molokai West, Windward Haleakala.
Small Craft Advisory until 6 PM HST Saturday for Kauai Northwest Waters, Kauai Windward Waters, Kauai Leeward Waters, Kauai Channel, Oahu Windward Waters, Kaiwi Channel, Maui County Windward Waters, Maalaea Bay, Pailolo Channel, Alenuihaha Channel, Big Island Windward Waters, Big Island Leeward Waters, Big Island Southeast Waters.

Big Island Now Weather is brought to you by Blue Hawaiian Helicopters.

Check out their Big Island Helicopter Tours today!

Data Courtesy of NOAA.gov